Cough and sputum are known to be caused by physical or chemical factors, such as cold air, foreign substances including pathological microorganisms, air pollutants, allergen and the like, and can be divided according to the causes as follow:
First, if cough receptors, in the arynx, trachea, bronchus, pharynx, paranasal sinuses, diaphragm and the like, are stimulated by physicochemical factors, the stimulation is delivered to cough center in the medulla of the brain, whereby coughing reflex occurs.
Second, if parasympathetic nervous system is activated by physical or chemical factors, a smooth muscle of the bronchus is constricted, whereby symptoms such as bronchial convulsion and bronchoconstriction may occur.
Third, inflammatory mediators and the like are released from mast cells by physical or chemical factors.
Therefore, removal of the above factors can suppress cough and sputum. However, most of drugs developed so far are mainly synthetic chemicals and thus, cause various side effects. Natural drugs developed for compensating such defects cannot exhibit excellent effect to suppress cough and sputum.
Meanwhile, asthma, which is a representative respiratory disease, repeatedly and spasmodically shows symptoms such as difficult breathing, cough, stridulous breathing, and the like. Asthma may be divided into cardiac asthma and bronchial asthma. Although incidence rate of asthma is varied according to a country, a human race, age, and the like, it was reported in England at 2007 that about 7.9% of adults, 13.7% of children and 9.4% of older adults are suffered from asthma. In Korea, the incidence has been increased due to change in life style, environmental pollution, increase in stress, and the like. Recently, the severity of asthma has been maximized, since environmental pollution becomes serious, the age of incidence of asthma becomes lowered and the symptoms are more long lasted.
The respiratory obstruction, which is characteristic to asthma, occurs by 3-steps. Specifically, a smooth muscle of bronchus is constricted, pulmonary mucosa becomes thickened, and sticky mucus pools in bronchus and bronchioles, thereby respiratory tract being obstructed. Among these steps, only the constriction of smooth muscle of bronchus can be easily recovered.
In the mechanism of occurrence of exogenous (allergenic) asthma, IgE is especially important, and IgG relates thereto in part. IgE releases mediators, such as, histamine, SRS-A, ECF-A, NCF, PAF, Kinin, PGs and the like, which activate mast cells to cause hypersensitivity reaction. Endogenic (non-allergenic) asthma, although its mechanism has not been clarified, appears to be mediated by autonomic nerve. Choline stimulation in endogenic patients causes isolation of a mediator such as histamine from a mast cell directly through end organs, increase in the secretion of goblet cells, expansion of pulmonary blood vessel, and constriction of trachea, bronchus and bronchioles, thereby increasing bronchial convulsion and secretion of mucus.
Fundamental treatment of asthma has not been developed yet, and various methods and drugs for preventing a spasm and complications are developed; however, they simply ameliorate symptoms and cannot fundamentally treat disease, and they may cause serious side effects.
In order to overcome such limits of the existing drugs, there is a demand for development of novel drugs capable of fundamentally treating the cause and effectively ameliorating symptoms of disease. However, various leucocytes, and cytokines and inflammatory mediators separated therefrom are involved in respiratory disease, and thus the effective treatment is difficult with a single-component compound. Therefore, natural extract having various ingredients and mechanisms can be an effective drug, and thus, there is a demand for development of a drug based on natural extract.